1. Field of the Invention
The present invention relates to generally to RFID cards, and more specifically, to a batteryless RFID card having a display.
2. Brief Description of the Related Art
In recent years, RFID cards are tags have become increasingly prevalent. The have been incorporated into many diverse fields. For example, RFID readers and cards have been incorporated into bill/coin acceptors (U.S. Pat. Pub. No. 2009/0321516 and 2009/0218395), tracking systems (U.S. Pat. Pub. No. 2010/0066497 and 2010/0019905), authenticatable badges (U.S. Pat. Pub. No. 2009/0289762), commodity displays (U.S. Pat. Pub. No. 2009/0295749) and luggage tags (U.S. Pat. No. 7,845,569). Advances have been made in some instances to provide RFID cards that receive power from a host device rather than having a battery incorporated into the card (U.S. Patent App. Pub. 2010/0033310, 2010/033307 and 2009/0206994).
Recently, efforts have been made to incorporate displays into RFID cards and tags. For example, in U.S. Patent App. Pub. No. 2010/0052908 entitled “Transient State Information Display in an RFID Tag,” a display is incorporated into an RFID card to show a transient state such as an age of a product. In the preferred embodiment disclosed in that patent, a card or tag reader provides a current date while the card provides the expiration date of the product. Based on a comparison of those two, an LED is illuminated to reflect the status of the product. The disclosure indicates that a variety of other types of displays may be used and also that the card may be active or passive. In another example, U.S. Patent App. Pub. No. 2010/0079416 entitled “Radio Frequency Identification (RFID), Display Pixel, and Display Panel and Display Apparatus Using RFID Display Pixel” discloses an RFID tag connected to an “RFID pixel” or plurality of “RFID pixels.” Another example is described in U.S. Patent App. Pub. No. 2009/0309736 entitled “Multifunction Contactless Electronic Tag for Goods.”